5Masses of objects in space are so great that astronomers often need to use scientific notation to describe them. The approximate masses of planets in the solar systemare given in the table.

6You can use the properties of exponents to multiply and dividenumbers expressed in scientific notation.Helpful Hint

7Additional Example 1: Division With Scientific NotationPluto was demoted from planet to dwarf planet in 2006, in part because of its small size. The mass of Pluto is about 1.3  kg. About how many times smaller is Pluto’s mass than Earth’s mass?Write a unit ratio, or divide, to find how many times.Write the ratio of Earth’s mass to Pluto’s mass.Divide the coefficients and divide the powers. Subtract exponents.Write the result in scientific notation.About 4.6  102, or about 460, times smaller.

8Check It Out: Example 1About how many times greater is the mass of Saturn than the mass of Earth? Write your answer in scientific notation.Write a unit ratio, or divide, to find how many times.Write the ratio of Saturn’s mass to Earth’s mass.Divide the coefficients and divide the powers. Subtract exponents.Write the result in scientific notation.Saturn’s mass is about  101 times the mass of Earth.

9Additional Example 2: Multiplication with Scientific NotationThe mass of Venus is about 66 times the mass of the moon. What is the mass of the moon? Write your answer in scientific notation.kgmass of moon66Solve for the mass of the moon..kg66mass of moonkgkgThe mass of the moon is about 7.4  kg.

10Check It Out: Example 2The average mass of a grain of sand on a beach is about 1.5  10–5 g. There are about 6.1  grains of sand in a beach volleyball court. What is the mass of the grains of sand in the beach volleyball court?Mass of grains of sands in court=(1.5 x 10-5 g)(6.1 x 1012 )= 9.15 x 107 g

11A number written in scientific notation has one factor greater than or equal to 1 and less than 10 and the other factor a power of 10.Remember!

12The volume was about 2.6  107 acre-feet.Additional Example 3: Addition and Subtraction with Scientific NotationThe water in Mono Lake, CA, was used for residents of LA. As a result, the lake’s volume, in acre-feet, dropped from 4.3  107 to 2.1  107 from 1941 to After becoming protected, the lake increased in volume by 5.0  106 acre-feet in the next 20 years. What was its volume in 2002?2.1 x xRewrite so that the powers are the same; then add.Write the result in scientific notation.The volume was about 2.6  107 acre-feet.

13Check It Out: Example 3How much greater is the mass of Neptune than the mass of Earth? Write your answer in scientific notation. Write your answer in scientific notation.kg kg kgkgkgkgNeptune’s is about 9.603 1025 kg greater in mass than Earth.

15Write your answer in scientific notation.1. The GDP of China in 2009 was about $8.7 x The GDP of Togo in 2009 was about $5.5 x 109.How many times greater was China’s GDP than Togo’s GDP in 2009?1.58 x 103 times greater2. A web site averages 4.5 x 104 hits per day. How many hits will it get in 3.6 x 102 days?1.62 x 107 hits

163. Two companies merged to form a new company. One company was worth $3.5 x 107. The otherwas worth $7.8 x 108. What is the combined value of the new company?$8.15 x 108